I have 2 indoor cats and battle this problem all the time. This is what is working for me. I wash the litter box about every other month sometimes more if it really starting to smell. I use a box with a cover. The litter is the most important part. I use the crystal cat litter, my favorite is the walmart brand. You have to stir this stuff daily and remove the poop (if I am home I remove it the second they leave the litter box). I will never go back to the clay types of litter again. ...»

Natures Miracle found in the pet stores and larger markets will help with kitty odors if they have sprayed the surrounding area. It comes in a white bottle. If you have access to a black light like we used when we were kids, turn it on when its dark in the room. All green glow is kitty smells from urine. The Matures Miracle will remove that.

one reason why we are dog people....

As Carrol mentioned above ...litter is the key ingredient to preventing smells. That and a dedicated human to change it as often as it is needed.

Walmart also carries a spray called Spot Out. It works really well for urine and vomit also. But the key is the litter and keeping the "chunks" out daily. I use the Walmart brand because it does not already have a smell. Some litters have a "fresh scent" that when mixed with urine is pretty bad.

I am with you KMS on this. Cats belong in barns, not in house. I had a neighbor who was very diligent in keeping her kitty box clean. They moved out not to long ago and the new people have begun pulling out the carpets and such and I allowed them to place that stuff in a dumpster I have on my property for disposal. After a few hot days I walked next to the dumpster and was taken over with a urine smell like no other. Never even smelled it in their house. But using air fresheners and the like must have masked the smells.

Arm & Hammer litter box deodorizer works great. It's a powder you sprinkle in the box before putting the litter and when you scoop.

If you have used the same litter box and it is plastic after time the plastic will absorb urine and it smells. Try replacing the litter box and wash it out whenever you clean it and see if this doesn't cut down on the smell.